01
What does dependsOnMethods do?
Show answer
It makes a test run only after specified tests pass, otherwise it is skipped. Use sparingly as it creates coupled tests.
Automation Test Engineer Interview Questions & Answers
40 questions for Automation Test Engineer interviews — 2 easy, 36 medium, 2 hard.
About the Automation Test Engineer role
Builds and maintains automated UI and API tests in Java, usually with Selenium, TestNG and REST Assured, and runs them through Maven and Jenkins. Works with developers and manual testers to pick what to automate and keeps the suite stable. Interviews test core Java, locators and waits, TestNG features, a simple REST Assured test and how you debug failures in CI.
Selenium WebDriver Core Java TestNG REST Assured Maven and Jenkins
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02
How do you build dynamic JSON request bodies without hard-coded strings?
Show answer
Use POJOs with a builder pattern or Lombok @Builder, so tests write User.builder().name("Ravi").role("QA").build(). For quick cases use a HashMap or Jackson ObjectNode. For large templates, keep a JSON file and change fields with a JSON library. Combine with a faker library for unique values. This avoids escaping issues and makes changes to the schema easy to update.
03
What is a DataProvider in TestNG?
Show answer
@DataProvider returns Object[][]; a @Test(dataProvider = "name") method runs once per row — the basis of data-driven tests, often reading Excel or JSON.
04
How do you share state between step definition classes in Cucumber Java?
Show answer
Use dependency injection. With cucumber-picocontainer (or Spring/Guice), create a context class such as TestContext holding the driver, page objects and scenario data, and add it as a constructor parameter in every step class. Cucumber creates one instance per scenario and injects the same object everywhere, so state is shared within a scenario but never leaks between scenarios. Avoid static fields because they break parallel runs.
05
How have you handled disagreement with a developer about whether something is a bug?
Show answer
Situation: a developer said a rounding difference in invoice totals was expected. Task: resolve it without friction. Action: I checked the requirement, found it specified rounding per line, and brought the document and a test case with expected values to a quick call with the BA. Result: the BA confirmed it was a bug, it was fixed, and we added the rule to the acceptance criteria.
06
How do you handle a test that is flaky only in headless mode?
Show answer
Set window size explicitly, use proper waits, check animations and viewport differences, and capture screenshots and logs to find timing issues.
07
What is a constructor and can it be overloaded?
Show answer
A special method that initialises an object. It can be overloaded with different parameters, and testers use it to pass the WebDriver into page classes.
08
How do you upload a file with Selenium?
Show answer
If the element is <input type="file">, use element.sendKeys("C:/path/file.pdf"). Use the Robot class or AutoIt only as a last resort for OS dialogs.
09
What are filters in REST Assured?
Show answer
Filters intercept requests and responses, similar to middleware. They implement the Filter interface and can add headers, refresh tokens, log traffic, or attach request and response details to Allure reports with AllureRestAssured. You add them with given().filter(myFilter) or globally in a RequestSpecification. Filters keep cross-cutting concerns out of individual tests.
10
An API returns 200 but your REST Assured assertion on a field fails with a null value. How do you debug it?
Show answer
Log the full response with then().log().all() to see the actual body. Common causes are a wrong JSON path, such as missing a wrapper like data, the field being in an array needing an index, a different content type like XML or HTML error page, or the field name having different case. Fix the path, and add a schema check so structure changes are caught clearly.
11
How do you measure and assert API response time in REST Assured?
Show answer
Use then().time(lessThan(2000L)) for a quick check or response.getTimeIn(TimeUnit.MILLISECONDS) to log the value. This measures client-side time, including network, so set generous thresholds and treat it as a smoke signal, not a performance test. For real load and latency percentiles, use tools such as JMeter, Gatling or k6.
12
How do you upload a file with REST Assured?
Show answer
Use multipart: given().multiPart("file", new File("src/test/resources/report.pdf"), "application/pdf").formParam("type", "invoice").when().post("/upload").then().statusCode(200). REST Assured sets the multipart/form-data content type automatically. Verify both the status and the response, such as the returned file id or size, and test edge cases like empty, oversized and wrong-type files.
13
How do you group tests?
Show answer
Tag tests with groups = {"smoke","regression"} and include or exclude them in testng.xml to run chosen sets.
14
Write a TestNG listener that logs test start and failure.
Show answer
public class LogListener implements ITestListener {
@Override
public void onTestStart(ITestResult r) {
System.out.println("START: " + r.getMethod().getMethodName());
}
@Override
public void onTestFailure(ITestResult r) {
System.out.println("FAIL: " + r.getName() + " - " + r.getThrowable());
}
}
// register with @Listeners(LogListener.class) or <listeners> in testng.xml
15
What is the use of the this and super keywords?
Show answer
this refers to the current object; super refers to the parent class, used to call parent constructors and methods.
16
How do you pass authentication in an API test?
Show answer
Use headers such as Bearer tokens, basic auth, API keys or OAuth flows; fetch a token in a setup step and reuse it.
17
What is the Optional class in Java and where is it useful in test code?
Show answer
Optional is a container that may or may not hold a value, introduced in Java 8 to avoid returning null. In test code it suits lookups that can legitimately find nothing, such as finding a row in a table or reading an optional config key. Callers use orElse, orElseThrow or ifPresent instead of null checks. For example, findRowByName(name).orElseThrow(() -> new AssertionError(name + " not found")) gives a clear failure message.
18
How do you handle authentication types in REST Assured?
Show answer
Basic auth uses auth().preemptive().basic(user, pass). Bearer tokens are set as a header: header("Authorization", "Bearer " + token). OAuth 2.0 can use auth().oauth2(token) after fetching the token from the token endpoint. API keys go in a header or query param. Fetch tokens once per suite or cache them with an expiry check rather than logging in before every test.
19
What is polymorphism and how does it show up in Selenium?
Show answer
One interface, many forms. WebDriver driver = new ChromeDriver() lets the same test code run on any browser class that implements WebDriver.
20
A dropdown option list loads only after typing three letters. How do you automate selecting a value?
Show answer
Type the text with sendKeys, wait for the suggestion list with visibilityOfAllElementsLocatedBy, then find the option whose text matches the required value and click it. Avoid selecting by index because suggestion order may change. If the list is virtualised, type more characters to narrow results. Verify the selected value in the input afterwards.
21
What are relative locators in Selenium 4?
Show answer
Locators such as above, below, toLeftOf and near that find elements by their position relative to another element.
22
What is git cherry-pick?
Show answer
git cherry-pick <commit> applies the changes of one specific commit onto your current branch, creating a new commit. It is useful when a fix on one branch, such as a locator fix on develop, is urgently needed on a release branch without merging everything else. Overuse creates duplicate commits and confusing history, so prefer normal merges when possible.
23
How do you run tests in parallel?
Show answer
Use TestNG parallel="methods | classes | tests" with thread-count, keep WebDriver in a ThreadLocal, and use Selenium Grid or a cloud grid for multiple browsers.
24
What is the @Factory annotation in TestNG?
Show answer
@Factory creates test class instances dynamically, each with different constructor data, so all tests in the class run once per instance. For example a factory can create LoginTests for chrome and firefox. It differs from DataProvider, which runs one method many times with different arguments. Factory is useful when a whole class should repeat for each configuration.
25
Where do you use OOP concepts in your framework?
Show answer
Encapsulation: private locators with public page methods. Inheritance: pages extend a BasePage. Polymorphism: the WebDriver interface for different browsers. Abstraction: utility layers hiding Selenium details.
26
Why do Selenium browser containers need a larger shm_size?
Show answer
Chrome and Firefox use shared memory at /dev/shm for rendering and inter-process communication. Docker gives containers only 64 MB of shared memory by default, which is not enough for modern pages, so the browser tab crashes with errors like session deleted because of page crash. Setting shm_size to 2g in Compose, or --shm-size=2g with docker run, fixes it. Mounting /dev/shm from the host is an alternative.
27
What is the difference between ThreadLocal and a synchronized block in Java?
Show answer
A synchronized block lets only one thread at a time run a piece of code that touches shared data, so threads wait for each other. ThreadLocal avoids sharing altogether by giving each thread its own copy of a variable. In parallel test frameworks ThreadLocal<WebDriver> is preferred because each thread needs its own browser, and locking would serialise tests. Always call remove() after quitting to avoid leaks in thread pools.
28
How does HashMap work internally?
Show answer
It uses the key's hashCode to find a bucket and equals to resolve collisions, giving O(1) average lookups; Java 8 converts long buckets into trees.
29
What is the difference between Comparable and Comparator in Java?
Show answer
Comparable defines the natural order inside the class (compareTo); Comparator defines custom orders externally (compare), useful for sorting test data in several ways.
30
How do you verify that an element is displayed, enabled or selected?
Show answer
Use isDisplayed(), isEnabled() and isSelected() on the WebElement before interacting or asserting.
31
Your Selenium tests in CI produce blank screenshots in headless mode. What could be wrong?
Show answer
The screenshot may be taken before the page renders, the window size in headless mode may be tiny, or the browser is crashing due to low shared memory in Docker. Set --window-size=1920,1080, use the new headless mode, wait for page content before capturing, and add --disable-dev-shm-usage or a larger shm size for containers.
32
POST vs PUT vs PATCH?
Show answer
POST creates a resource, PUT replaces the whole resource (idempotent) and PATCH updates part of it.
33
How do you handle waits inside page objects?
Show answer
Put explicit waits in page methods or BasePage helpers, not in tests. For example click() waits for elementToBeClickable before clicking, and a page's isLoaded() waits for a key element. Avoid Thread.sleep and avoid mixing implicit and explicit waits. Keep the timeout configurable so CI can use a slightly longer value than local runs.
34
How do you validate a JSON response in REST Assured?
Show answer
Use then().statusCode(200).body("data.id", equalTo(5)), or extract() the response and assert fields with JsonPath.
35
Which reporting tools do you use?
Show answer
TestNG reports, ExtentReports and Allure give charts, screenshots and logs that are easy to share with the team.
36
Describe a time you improved the maintainability of an automation framework.
Show answer
Situation: our suite had duplicated locators across 200 tests and each UI release broke many of them. Task: reduce maintenance effort. Action: I introduced page objects and components for the top ten pages, added data-testid attributes with the developers and wrote a short guide. Result: fixing a UI change went from half a day to under an hour, and new joiners wrote tests faster.
37
How do you validate an XML response in REST Assured?
Show answer
// REST Assured uses GPath for XML as well as JSON
given()
.accept(ContentType.XML)
.when()
.get("/orders/42")
.then()
.statusCode(200)
.contentType(ContentType.XML)
.body("order.@id", equalTo("42"))
.body("order.items.item.size()", equalTo(3))
.body("order.status", equalTo("SHIPPED"));
38
How do you retry failed tests in TestNG?
Show answer
Implement IRetryAnalyzer with a retry count and attach it through the test annotation or a listener to rerun flaky tests.
39
What is method overriding and where is it useful in frameworks?
Show answer
A subclass redefines a parent method. Frameworks use it to customise base behaviour, such as overriding a wait or click method in a base page class.
40
What are try-with-resources and why use them?
Show answer
A try block that automatically closes resources such as file readers or streams, preventing leaks without a finally block.
Frequently asked questions
What does a Automation Test Engineer do?
Builds and maintains automated UI and API tests in Java, usually with Selenium, TestNG and REST Assured, and runs them through Maven and Jenkins. Works with developers and manual testers to pick what to automate and keeps the suite stable. Interviews test core Java, locators and waits, TestNG features, a simple REST Assured test and how you debug failures in CI.
Which skills are tested in a Automation Test Engineer interview?
Expect questions on Selenium WebDriver, Core Java, TestNG, REST Assured, Maven and Jenkins. Most rounds also ask you to explain a project and solve one practical problem live.
How do I prepare for a Automation Test Engineer interview?
Revise Selenium WebDriver, Core Java for Testers, TestNG Framework, REST Assured first using the topic sheets, practise the questions on this page aloud, then do one full mock interview to practise timing.
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